Equivalent observation age. Black: PSNR (left) and correlation (right) over the unobserved sector of the target at t scored against the target at t ± Δ. Dashed: HelioFill (15.50 dB, ρ = 0.520), which crosses the curves at ≈29 hr and ≈49 hr. Square: persistence at its mean information age. Triangle: the nearest training frame under a random split (median gap 1 hr), the information that protocol exposed (Appendix B).